Having been a few times to the original Oishii in Chestnut Hill (and loved it) I decided to try out the new Oishii in the South End last night. No problems getting a reservation for 6 folks at the height of the Friday rush - while the place was crowded, it was not incredibly so, and I did not see many people waiting for tables (unlike, say, a place like Toro). I noticed they take reservations on opentable as well.
So, was it worth it? Hard to say. Frankly, the prices are ridiculous. (This is coming from someone who lived in Japan and knows what good sushi should cost.) At first glance at the menu many sushi items are in the $4-6 range, which sounds reasonable, until you realize that that is _per piece_, not per 2 pieces. The rolls run from $12 to $30 if I recall correctly. In the end we ended up spending about $100 per person which is not too bad, but we did not drink very much and definitely were not stuffed when leaving; we could have easily spent another $20-30 a head.
The fish is excellent quality and everyone agreed it was some of the best sushi they have had in Boston. We had a range of nigiri including toro, aji, hamachi, sake toro, uni, scallop, tobiko, and unagi and everything was great. The maki rolls we ordered - including the white tiger maki (tuna and avocado wrapped in white seaweed with a spicy mayo), "Oishii Sashimi Maki" which was large pieces of sashimi held together with cucumber (no rice!), and lobster maki (wrapped in marinated seaweed) were good, but often large, cumbersome to eat, and with too many contrasting flavors. In contrast the execution at the original Oishii seemed to be far more consistent and less "over the top." They do have a very interesting selection of fish and even had some live uni at the sushi bar which one of the chefs was happy to prod for us to show that it was alive.
Part of my hesitation comes from the space, as well. It is very dark, spartan, and trying a bit too hard to be "hip". The overall effect is a bit cold, rather than feeling cozy and welcoming. Service was very good. The sake list was excellent though the cocktails were uneven -- best to stick to sake.
Would love to hear how others feel about the new Oishii. I was surprised how different it was in style _and_ substance to the original, even though I had it on the boards!